1. Field of the Invention
The invention comprises the use of one or more polyamide-5 (Orgasol Caresse) to increase the care and/or efficacy properties of cosmetic or dermatological preparations, such as water proofness, long-term stability, skin moisture and stickiness.
2. Discussion of Background Information
Nylon is a 100% synthetic fiber, which was first introduced by Du Pont in 1939. Nylon has been adopted as a generic name for linear, aliphatic polyamides. Thus Nylon 4, Nylon 11, etc. designate chemically correctly polyamide/polyamide fibers PA4, PA11.
The original Nylon is chemically a PA66, i.e., a polycondensation product of hexane-1,6-diamine and adipic acid.
In cosmetics, Nylon types 6, 11, 12 and 66 as well as Nylon copolymers 12, 6, 66 are known. These Nylon types have in particular swelling properties, i.e., reduce the bulk density of cosmetic agents, opacifying properties, i.e., reduce the transparency and the light transmittance of cosmetic agents, and viscosity-regulating properties, i.e., increase or reduce the viscosity of cosmetic agents.
Nylon types 6-14 are known from Arkema under the trade names Orgasol® and Orgasol Caresse®. The production of these polyamide types, in particular PA 6, PA6-6, PA 12, PA 6-12 and PA 6-14, is described in US 20050197446, US 20060041041 and US 20060205883 of Arkema.
Orgasol Caresse® thereby represents the polyamide-5 compounds according to INCI, which can be used, for example, to increase the sunscreen factor in cosmetic sunscreen products (parfums cosmetique, no. 198, December 2007, p. 72).
Orgasol types are available as ultra-fine powders, with in part small particle sizes. The use is known in foundations, lipsticks, mascara, eye shadows and nail polishes, likewise in gel creams, skin moisturizing agents, lotions, sunscreen preparations or after-shave formulations.
The Nylon-6 types are lipophilic and make it possible for the preparations containing it to have a silky feeling on the skin. Nylon-12 types are less lipophilic and impart a dry feeling on the skin.
Orgasol Caresse®, also sold as Orgasol Type 4000 EXD, was specifically developed for aqueous formulations. It comprises fine polyamide copolymer (6-12) powder with an average particle size of 10 Orgasol Caresse® has a higher absorption capacity for water as well as for oil compared to the other Orgasol types.
It thus renders possible the better dispersibility of the cosmetic preparations and gives the preparation a certain richness, even with a small oil phase.
Sunscreen preparations contain a UV filter, which filters certain UV rays out of sunlight in order to protect the skin or the hair from their harmful effects. Known UV filters are substances from the positive list of the UV filters (Annex VII of the EC Cosmetics Directive) and are preferably used.
A measure of the effectiveness of UV protection is represented for the purposes of the present invention for example by the sun protection factor (SPF).
The sun protection factor (SPF) indicates the increased time of exposure to the sun's rays made possible through use of the sunscreen composition. It is the ratio of the erythema threshold time with sunscreen composition to erythema threshold time without sunscreen composition.
The effectiveness of UV-A protection is normally tested by using the IPD method (IPD=immediate pigment darkening). This involves—similar to the determination of the sun protection factor—the determination of a value which indicates how much longer skin protected with the light protection composition can be exposed to UV-A radiation until the same pigmentation occurs as with the unprotected skin.
Another test method which has become established throughout Europe is the Australian standard AS/NZS 2604:1997. This involves the measurement of the absorption of the preparation in the UV-A range. To comply with the standard, the preparation must absorb at least 90% of the UV-A radiation in the range from 320 to 360 nm.
In general, the light absorption behavior of light-protective filter substances is very well known and documented, especially as there are positive lists for the use of such substances in most industrialized countries, which impose very strict standards on the documentation.
The use concentration of known light-protective filter substances present in the form of a solid, is, however, often limited—especially in combination with other substances to be dissolved. This therefore gives rise to certain technical difficulties relating to formulation in achieving relatively high sun protection factors or UV protection performance.
In particular, the formulation of the preparations with physical filters, such as TiO2, is difficult and leads to instabilities.
It is furthermore disadvantageous that sun protection preparations frequently lose their protective effect after contact with water during bathing or swimming due to the “wash off” effect.
The object of the present invention is therefore to provide a sun protection preparation which, in addition to a cosmetic acceptance, has an improved water proofness on the skin.